Miter-curve cutter



2 SHEETS-SHEET I.

Patented Feb. 14, 1922.

A. F. NATHAN: MITER CURVE CUTTER.

APPLICATION FILED JUNE 26,1918. 1,406,481

INVENTOR (wax ATTORNEY Na M w:

A. F. NATHAN. MIT'ER CURVE CUTTER. APPLICATION FILED JUNE 26.1918.

1,406, 18 1- Patented Feb. 14, 1922.

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, r nk 1 G I W z i J J A INVENT R ATTORNEY UNITED STATES PATENT. ()FFICE.

ALBERT F. NATE-IAN, OF PLAZNFIELD, NEW JERSEY.

METER-CURVE CUTTER.

To all who 1n it may concern Be it known that l, ALnnnr F. NATHAN, a citizen of the United States, and residing at Pia-infield, in the county oi Union and State of New Jersey, have invented a new and improved Miter-Curve Cutter, of which the following specification is a full disclosure.

This invention proposes a mechanism suitable for cutting sheet-metal into elbow sections of large dimensions; i. e, for cutting so-called miter-curves. Heretotore, this has been done eitherby means of handshears, or by one or the other of the machines described in the U. S. Patents Nos. 729,9G-it and 730,874 issued to Scherer and to Chambers and Bullard, respectively. Both of these machines depend upon a single track: to direct the movements and control the positions of the cutters; the carriage (on which the cutters are supported) in each case is held on the track by two .pairs of horizontal rollers on the erroneous supposition that a line connecting the pairs will be main tained parallel to a'tangent at the various stations along the curve. It may also be noted that, owing to the continually varying radius of the miter-curve, the tour rollers cannot geometrically be constantly in rolling-contact with the track. Consequently, they must provide sufficient lost-motion or backlash to prevent binding at stations demanding the widest separation. Any departure from the true tangent creates a draw in the line being cut, and any lost motion causes a divergence from the line of the mitercurve.

The object of this invention is to create a mechanism, based on geometrically correct ,principles, which will so guide the cutters as to maintain their cutting-point accurately coincident with a true miter-curve, and at the same time invariably maintain the cutting-plane (direction of out) precisely tangential to the curve.

This may best be explained in connection with the drawings, of which; Fig. 1, is a geometrical lay-out of this invention; Fig, 2, is a side elevation of a practical embodiment thereof; while Fig. 8, is a plan of the machine.

Let DEF-c represent in elevation a cylinder corresponding in diameter to the pipe-section for which an elbow is to be made. A-B is the trace of a plane cutting it at the angle desired for the joint of the elbow; said angle being 15 in this in-' Specification of Letters Patent.

Patented Feb. 14, 1922.

1818. Serial No. 242,045.

stance. The semi-circle H-Oll represents a plan of half the cylinder. It may be shown that the entire miter-curve consists of four identical sections disposed reversely and in opposition respectively. Hence it will sullice to describe the layout for one quadrant of the curve; e. g, the portion vithin the rectangle l\l-O-11-N, in

2 the length of 0 11 will be T. Hence, divide the radius K--11 into seven equal parts, and lay out eleven of these on the quadrant-circle, as 1, 2", 3", l, etc, and also develope these as points 1, 2', 3, 4, etc, along the line U-1L Each of the eleven verticals from these points willintersect the corresponding one of the eleven equi-spacedhorizontals (between OO on line MK) at the stations 0, 1, 2, 3, a, etc. on the miter-curve shown in dotted lines. In this manner, the miter-curve is accurately defined.

It nowibecomes necessary to locate the tangents for these stations. Take station 6, for example. Draw the tz ngent 0 -6" -6 through the point 6" on the quadrantcircle O-611. This may be very accurately done by drawinga radius from K bisecting the angle OK-6; and another ra-dius bisecting the complementary angle 6-'7c11. The intersections of those radii with the horizontal and vertical lines through 0 accurately locate the points 0 and 6. About 0 as a center, draw the arc ee ;'the latter point being its intersection with the horizontal. Drop a vertical from 0" and note where it intersects the cuttingplane A-B. A line drawn through these last located points 0 and a will be parallel to the tangent to be drawn through the station 6 on the miter-curve. Therefore, draw such tangent 6m-66e. Another way is to locate the point t on the horizontal D-O by measuring 6t equal to 6"-e Then, a line drawn through 6 on the miter-curve and 25 will be the tangent to the miter-curve at the station 6.

In this manner, tangents may be drawn at each of the stations 1, 2, 3, 4, 5, 6, etc., for all points of the miter curve. .It may be noted, however, that the labor of developing each tangent in the manner aforesaid may be greatly curtailed by observing that the miter curve is composed of four identical length equal to Since 71 contact.

- true to o the cutters are in sections; each section being similar to that correspzmding to a quadrant of the circle; i. e., similar to the portion of the curve within the rectangle ()llN-h"l. The tangents for the various other sections oi the curve can, therefore, be obtained merely by duplicatin the tangents in the aforesaid rectangle in each of the other three corresponding retangles. For example, the'layout in the re -tangle TO-MP is exactly that above (lGSClllJGCl, the only difierence liieing that the latter rectangle is produced by rotatin; the first rectangle bodily. through an angle of 180 in the plane oi the paper. Likewise, the layout tor the rectangle to the right of that first named obtained by rotating the rertangle O-l.lN-M bodily through 180 about the line 1 lN as an axis. Ti e have now obtained all of the tangents throughout the length oi the curve. he proposition now redures merely to the de. velopment oi two tra ks, each of which the locus of a point having a fixed definite relation, to the tangent. Preferably, as :1 matter oil convenience in layout, points are selected equally distant from the centre of the tangent; i. e., its point oil contact with the miter curve. Thus, a point 6 is the same distance to the left of the point 6 as the point 6 is to its right. By laying out these various points on the various tangents, we obtain a curve shown in dashes and indirated by the points O, 1 2 3, etc., for the left hand end oi? the tangent; and a similar curve Q 1, 2", 3, etc, for the right hand portion of the tangent.

It will now be evident that it the afore said dotted. rurves could he used as tracks, and it the above defined points on the tangent could be maintained in coincidence with said curves, then they would serve to maintain the centre of the tangent in coincidence with the dotted miter curve, and would also keep the tangent truly tangential to the w-iu've at all oi its stations of contact. Aerordingly, it a carriage could be arranged in fired relation to the travelling tangent so as be guided and located thereby, then such carriagecould be used tm'supporting and "guiding suitable conventional rotary cutters such as are employed in the shearing of sheet metal. Such cutters, however, it mounted on the carriage so as to be vertical from the point 6, when the carriage is in the position shown in dotted lines and when the axes the vertical plane of the line S il then will the cutters be caused not only to trace the miter curve in true coincidence therewith but also to be ac curately tangential thereto at all points of diecordingly. the sheet metal, by such'a mechanism, must necessarily be cut pattern and without any draw of the metal.

If it be desired to use'the aforesaid loci directly as tracks, it will be observed that they must be arranged in dillerent planes on account of the fact that these curves cross. In fact, one curve is virtually the same as the other save for beingtranslated in the direction of the line X-X. It may be more (onvenient, therefore, to arrange the tracks in the same plane and this can readily be done by striking an are about 6 as a center from the points 6 and 6. At definite distances from these points 6 and 6 are located the centers of similar rollers Z and Z.

In putting this invention into practical ellect, a rotary shearing mechanism of a conventionaltype will be provided with two sets of guide rolls for the two guideways or tracks, respectively. Means will be provided for clamping a blank of sheet metal to hold it under the action of the cutters. The mechanism may be conveniently arranged on a bench, such as indicated by C,

which provides an upper table or platform and a lower shelf: J. On this lower shelf is mounted a plate or frame L provided with dual track Vi -JV and any suitable fastening means such as the bolts a may be employed to hold it onto said shelf. The rotary shears consist of the usual U-shaped casting Q, through the upper and lower legs of which extend shafts supporting the retary cutters 7) and 0 at the one end andthe gears d and e at the other end; a hand crank f being usedto impart rotation to the shears.

towards the cutting end of the shearsysaid roller serving to support the rear end of the casting as it swings back and forth during its travel under the guidance of the track system aforesaid. The parts are so proportioned and arranged that a vertical line let fall from the cutting point of the cutters will coincide with the miter curve to which the two tracks W and W are systematically related in the manner disclosed in the'foregoing, so that the cutting point willtrace a true miter curve during the travel of the casting y The means for holding the blank of sheet metal U and presenting it to the cutting action of the rotary cutter may conveniently consistof a clamping plate V mounted over the upper table I near the forward margin thereof. This clamping plate may be 0perated by means of toggles 7c and Z operated from a rock-shaft m' which isrotated by a suitable hand lever a. The rock-shaftis'in turn journalled in the posts 0 and upstanding from the table I. The details of the foregoing elements may be varied widely to conform to any desired requirements,

Without further elaboration, the foregoing will so fully reveal the gist of this invention that others can, by applying current knowledge, readily adapt it for various applications without omitting certain fea-' tures that, from the standpoint of the prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should be and are intended to be comprehended within the meaning and range of equivalency of the following claims.

Having thus revealed this invention I claim as new and desire to secure the following combinations of features and elements, or equivalents thereof, by Letters Patent of the United States 1. A miter-curve cutting-machine combining a clamp for sheet-metal; a rotary-cutter; a supporting carriage therefor providing a first guide and also a second guide widely spaced apart; a first guide-way coacting with said first guide; and a second guideway coacting with said second guide, said two guide-ways being mutually so contoured as to cause the cutting point of the rotary-cutter.

to trace a true miter-curve and maintain the cutting plane of sand rotary-cutter accurately tangential to said curve throughout the travel of the carriage.

2. A miter-curve cutting-machine combining a travelling carriage; a pair of guideways each curved respectively in predetermined relation with the loci of the extremities of a line of fixed length on said carriage travelling tangentially to a miter curve and with a predetermined point maintained in coincidence with said miter-curve; guiding elements provided by said carriage to maintain it in such relation to said guide ways that the extremities of said line will be maintained in-the aforesaid predetermined relation with said respective guideways; a pair of rotary-cutters so supported by said carriage that their cutting plane coincides with said tangent line and their'cutting point vertically over the said predetermined point; and clamping means for presenting sheet-material horizontally to said cutters.

3. A miter-curve cutting-machine combining a travelling-carriage; a pair of rotarycutters journaled thereon; guiding-elements spaced widely apart and mounted on said carriage; a first and a second guide-way eooperating independently with said guidingelements and so curved and disposed as to cause the cutting-points of said rotary-cutters to trace a miter-curve during the travel of said carriage and to maintain their cutting plane in tangential relation to said miter-curve throughout the travel of said carriage.

In witness whereof, I hereunto subscribe my name, as attested by the two subscribing witnesses.

ALBERT F. NATHAN. 

